Methods and systems for super-resolution optical imaging using high-index of refraction microspheres and microcylinders

ABSTRACT

The present invention provides super-resolution optical imaging methods and systems, including: providing a sample to be optically imaged; providing a plurality of microstructures disposed substantially adjacent to a surface of the sample to be optically imaged; and providing a material disposed about the plurality of microstructures; wherein the plurality of microstructures have a first index of refraction; and wherein the material disposed about the plurality of microstructures has a second index of refraction that is substantially less than the first index of refraction of the plurality of microstructures. The plurality of microstructures include one of a plurality of microspheres and a plurality of microcylinders.

CROSS-REFERENCE TO RELATED APPLICATION(S)

The present patent application/patent is a continuation (CON) ofco-pending U.S. patent application Ser. No. 14/042,834, filed on Oct. 1,2013, and entitled “METHODS AND SYSTEMS FOR SUPER-RESOLUTION OPTICALIMAGING USING HIGH-INDEX OF REFRACTION MICROSPHERES AND MICROCYLINDERS,”which is a continuation-in-part (CIP) of co-pending U.S. patentapplication Ser. No. 13/909,385, filed on Jun. 4, 2013, and entitled“METHODS OF SUPER-RESOLUTION IMAGING BY HIGH-INDEX MICROSPHERES AND/ORMICROCYLINDERS,” which claims the benefit of priority of U.S.Provisional Patent Application No. 61/656,710, filed on Jun. 7, 2012,and entitled “METHODS OF SUPER-RESOLUTION IMAGING BY HIGH-INDEXMICROSPHERES,” the contents of all of which are incorporated in full byreference herein.

STATEMENT OF GOVERNMENT SUPPORT

The present invention was made with Government support pursuant to awardnumbers ARO W911NF-09-1-0450 and NSF ECCS-0824067 by the Army ResearchOffice (ARO) and the National Science Foundation (NSF), respectively.Accordingly, the Government has certain rights in the present invention.

FIELD OF THE INVENTION

The present invention relates generally to optical imaging methods andsystems. More specifically, the present invention relates tosuper-resolution optical imaging methods and systems using high-index ofrefraction microspheres, microcylinders, and the like.

BACKGROUND OF THE INVENTION

It is well known to those of ordinary skill in the art that theresolution of a far field optical imaging system is limited by thediffraction limit. The diffraction-limited spot size is approximatelyλ/(2×NA), where A is the free space wavelength and NA=n sin θ is thenumerical aperture of the lens used, where n is the refractive index inthe object space and θ is the half-angle subtended. It is also wellknown to those of ordinary skill in the art that information about thenanoscale (i.e. sub-wavelength) structure of an object being imaged isencoded in its optical near field. However, conventional optical imagingsystems, such as lenses, cannot capture these evanescent fields, whichdecay exponentially in the vicinity of the surface of the object. Thisis the main reason why conventional far field optical imaging systemshave diffraction-limited optical resolutions. A practical system forsuper-resolution optical imaging must be capable of capturing these nearfield optical components, and then converting them into propagatingmodes that can be used for imaging the objects in far field, but withresolution exceeding the diffraction limit. An ideal system forsuper-resolution optical imaging must also be able to magnify asub-diffraction limited image. Thus, improved systems forsuper-resolution optical imaging are still needed in the art.

BRIEF SUMMARY OF THE INVENTION

In various exemplary embodiments, the present invention providesimproved methods and systems for the super-resolution optical imaging ofnanoscale objects using high-index of refraction microspheres,microcylinders, and the like. For example, the present disclosuredefines high-index of refraction microspheres as microspheres with anindex of refraction (n) larger than 1.8. Previously, super-resolutionoptical imaging has typically been explored and demonstrated usingmicrospheres with a relatively low n˜1.46-1.50. In accordance with thepresent invention, the distinctive feature of high-index of refractionmicrospheres is their ability to provide super-resolution opticalimaging in cases where the microspheres are embedded in a material withan index of refraction that is substantially less than that of themicrospheres. This is demonstrated for barium titanate glassmicrospheres with n˜1.9-2.1 immersed in isoprapanol with an index ofrefraction of 1.37, for example. However, such super-resolution opticalimaging using high index of refraction microspheres can be achievedusing different liquids, polymers, or other transparent orsemi-transparent materials for infiltration, as is described in greaterdetail herein below. Advantageously, this allows for very broadapplications in nanoplasmonics, nanophotonics, biomedical microscopy,microfluidics, and for the super-resolution optical imaging of metallicand/or semiconductor nanostructures and/or individual cells, forexample, which were not possible using previously developed methodsbased on the use of low-index of refraction microspheres. The methodsand systems for super-resolution optical imaging of the presentinvention can be realized using microspheres (or microcylinders or thelike) with diameters varying from several wavelengths (˜1-2 μm in thevisible regime) up to thousands of wavelengths. The methods and systemscan be realized in at least two exemplary embodiments. In one exemplaryembodiment, the high-index of refraction microspheres (or microcylindersor the like) are deposited on the surface of the object being imaged andcovered with a liquid or semi-solid. In another exemplary embodiment,the high-index of refraction microspheres (or microcylinders or thelike) are embedded in a material with the ability to solidify aboutthem, thereby forming a thin film that can be transferred and attachedto the surface of the object being imaged. Both exemplary embodimentsotherwise use conventional microscopy tools, such as microscopes, foroptically imaging the nanoscale features of the objects being imaged byvisualization through the microspheres.

In one exemplary embodiment, the present invention provides asuper-resolution optical imaging method, including: providing a sampleto be optically imaged; providing a plurality of microstructuresdisposed substantially adjacent to a surface of the sample to beoptically imaged; and providing a material disposed about the pluralityof microstructures; wherein the plurality of microstructures have afirst index of refraction; and wherein the material disposed about theplurality of microstructures has a second index of refraction that issubstantially less than the first index of refraction of the pluralityof microstructures. The material disposed about the plurality ofmicrostructures is one of a liquid material, a semi-solid material, anda solid material. The plurality of microstructures include one of aplurality of microspheres and a plurality of microcylinders. Optionally,the plurality of microstructures are disposed substantially adjacent tothe surface of the sample to be optically imaged and subsequently thematerial is disposed about the plurality of microstructures.Alternatively, the plurality of microstructures are disposedsubstantially adjacent to the surface of the sample to be opticallyimaged after the material is disposed about the plurality ofmicrostructures (the material may also be disposed adjacent to thesurface of the sample to be optically imaged first, then the pluralityof microstructures are disposed adjacent to or in the material, etc.).The first index of refraction is equal to or greater than about 1.8.Again, the second index of refraction is less than the first index ofrefraction. The method also includes optically imaging the samplethrough the plurality of microstructures and the material disposed aboutthe plurality of microstructures using an objective of a microscope. Theplurality of microstructures and the material disposed about theplurality of microstructures are disposed in a near field region of thesample to be optically imaged. The plurality of microstructures havediameters or major dimensions between a wavelength of light utilized toseveral thousand wavelengths of the light utilized. The plurality ofmicrostructures are made of a glass material, a crystalline material,barium titanate, chalcogenide, titania, zirconium oxide, zinc oxide,silicon, or the like. The material disposed about the plurality ofmicrostructures includes liquids, solids, semisolids, water,isopropanol, alcohols, cyclohexane, toluene, PDMS, gels, polymers,epoxies, or the like. Optionally, the plurality of microstructures andthe material disposed about the plurality of microstructures form atransferrable component that is selectively disposed substantiallyadjacent to the surface of the sample to be optically imaged.

In another exemplary embodiment, the present invention provides asuper-resolution optical imaging system, including: a plurality ofmicrostructures disposed substantially adjacent to a surface of a sampleto be optically imaged; and a material disposed about the plurality ofmicrostructures; wherein the plurality of microstructures have a firstindex of refraction; and wherein the material disposed about theplurality of microstructures has a second index of refraction that issubstantially less than the first index of refraction of the pluralityof microstructures. The material disposed about the plurality ofmicrostructures is one of a liquid material, a semi-solid material, anda solid material. The plurality of microstructures include one of aplurality of microspheres and a plurality of microcylinders. Optionally,the plurality of microstructures are disposed substantially adjacent tothe surface of the sample to be optically imaged and subsequently thematerial is disposed about the plurality of microstructures.Alternatively, the plurality of microstructures are disposedsubstantially adjacent to the surface of the sample to be opticallyimaged after the material is disposed about the plurality ofmicrostructures. The first index of refraction is equal to or greaterthan about 1.8. Again, the second index of refraction is less than thefirst index of refraction. The system also includes an objective of amicroscope for optically imaging the sample through the plurality ofmicrostructures and the material disposed about the plurality ofmicrostructures. The plurality of microstructures and the materialdisposed about the plurality of microstructures are disposed in a nearfield region of the sample to be optically imaged. The plurality ofmicrostructures have diameters between a wavelength of light utilized toseveral thousand wavelengths of the light utilized. The plurality ofmicrostructures are made of a glass material, a crystalline material,barium titanate, chalcogenide, titania, zirconium oxide, zinc oxide,silicon, or the like. The material disposed about the plurality ofmicrostructures includes liquids, solids, semisolids, water,isopropanol, alcohols, cyclohexane, toluene, PDMS, gels, polymers,epoxies, or the like. Optionally, the plurality of microstructures andthe material disposed about the plurality of microstructures form atransferrable component that is selectively disposed substantiallyadjacent to the surface of the sample to be optically imaged.

In a further exemplary embodiment, the present invention provides asuper-resolution optical imaging device, including: a plurality ofmicrostructures; and a material disposed about the plurality ofmicrostructures; wherein the plurality of microstructures have a firstindex of refraction; wherein the material disposed about the pluralityof microstructures has a second index of refraction that issubstantially less than the first index of refraction of the pluralityof microstructures; and wherein the plurality of microstructures and thematerial disposed about the plurality of microstructures collectivelyform a transferrable component that is configured to be disposedsubstantially adjacent to a surface of a sample to be optically imaged.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is illustrated and described herein with referenceto the various drawings, in which like reference numerals are used todenote like method steps/system components, as appropriate, and inwhich:

FIG. 1 is a schematic illustrating one exemplary embodiment of thepresent invention using microspheres disposed on the surface of anobject being imaged and submerged in an infiltrating liquid orsemi-solid material;

FIG. 2 is a schematic illustrating another exemplary embodiment of thepresent invention using microspheres disposed within another materialhaving a substantially lower index of refraction, thereby forming a thinfilm that can be disposed substantially adjacent to an object beingimaged;

FIG. 3 illustrates (a) a scanning electron microscope (SEM) image of acommercial Blu-ray® disk with 200-nm width stripes separated by 100-nmwidth grooves, (b) BTG microspheres with diameter sizes˜2-20 μm immersedin isopropanol used to resolve the sub-diffraction features of thesample (a), and (c) imaging with an optical microscope with 20× andNA=0.4 objective lens through the microspheres; and

FIG. 4 illustrates (a) a BTG microsphere with a diameter˜50 μm and indexof refraction n=2.1 immersed in isopropanol, (b) a corresponding imageillustrating sub-diffraction features of a commercial Blu-ray® disk with200-nm width stripes separated by 100-nm width grooves, (c) a soda-limeglass microsphere with a diameter˜50 μm and index of refraction n=1.51in air, and (d) a corresponding image illustrating very poorly resolvedsub-diffraction features of the same Blu-ray® disk with a weak contrastand poor image quality.

DETAILED DESCRIPTION OF THE INVENTION

The processes for the collection of near field spatial harmonics andtheir conversion into propagating fields are typically realized instructures with sophisticated engineering designs. Previously,super-resolution optical imaging has been realized using near fieldprobes, solid immersion lenses (SILs), novel metamaterials, plasmongratings, and various modified fluorescence-based techniques, such asstimulated emission depletion (STED). These methods and devices,however, have various drawbacks in super-resolution optical imagingapplications. Near field probes have low transmissions, they can beeasily damaged by contact with a surface, and they require sophisticatedand precise positional control. Solid immersion lenses use an immersionlens made from a high-index of refraction material. There are two cutsmade in a solid sphere that yield aberration free imaging. If one cutsthrough the middle of the sphere, the resulting hemispherical lensenhances the numerical aperture of an optical system by n, the index ofrefraction of the lens material. If one cuts a slice at a distance R+R/nfrom the top of a sphere of radius R, the resulting lens enhances thenumerical aperture by n². Although SIL technology represents asignificant improvement of optical imaging technology, and has allowedthe development of optical devices with NA>1, it remains impractical forresolving details under 100 nm. In particular, one of the drawbacks ofthis technology is that the base of the hemispherical or super-sphericalSIL must be placed in a near field vicinity of the object, but there isno convenient way to control (and in many cases even to know) thenanometric separation between the surface of the lens' base and theinvestigated surface. Commercially, only SILs with largemillimeter-scale dimensions are available, due to difficultiesassociated with manufacturing individual SILs with smaller dimensions.It is, however, rather difficult to control the nanometric separationbetween millimeter-scale surfaces. Much smaller micron-scale SILs havebeen fabricated using rather complicated surface treatments; howeversuch micron-scale SILs (sometimes called nano-SILs in the literature)necessarily have a permanently fixed position at the surface of thestructure. Due to difficult fabrication and fixed position, suchmicron-scale SILs have not found wide application. Novel metamaterialsand plasmon gratings can operate only in a narrow range of wavelengthsand they are very difficult to manufacture. Various modifiedfluorescence-based techniques, such as STED, are, of course, applicableonly to fluorescent materials.

In this context, super-resolution optical imaging using microspheres,microcylinders, or the like provides a simple and superior way ofachieving sub-diffraction resolution. In comparison with SILs, theadvantage of these microstructures with a circular symmetry is theextremely compact size of their contact region with a surfaceunderneath. In a hard sphere model, the contact region is represented bya single point, whereas for cylinders it is represented by a line. In areal physical situation, the contact region has finite dimensions, butit is significantly smaller than that of SILs. This makes it much easierto make sure that the spheres or cylinders are actually in contact withthe investigated surface. This can be achieved, for example, by lightlypressing these microstructures into the investigated surface. The simplegeometry of the problem allows for an estimation that, in the vicinityof the contact region, the spherical or cylindrical surface is locatedwithin the extent of the evanescent fields produced by various surfacenanostructures, which can be used for their super-resolution opticalimaging. In this methodology, the surface of an object can be consideredas a collection of nanoscale dipole antennas that contain informationabout its structure in the optical near field. It has been demonstratedthat if a microsphere in an air environment with index of refraction (n)around 1.46 and size from 2 to 9 μm is placed in a contact position, itsnear contact region can convert the high frequency spatial harmonics ofthe evanescent field into propagating modes. This allows for thesuper-resolution imaging of these high-frequency components by looking“through the microsphere” into a virtual image produced by suchmicrosphere at a certain depth below the surface of the structure. Anadditional advantage of this technique is that it can be performed usingwhite light illumination. Both far field resolution between λ/8 and λ/14and magnification between ×4 and ×8.2 have been demonstrated using suchwhite light nanoscopy. In addition, it has been shown that thesuper-resolution capability of this technique can be reinforced bysemi-immersing the corresponding microspheres in a liquid droplet,producing a sharper contrast with a comparatively smaller magnificationfactor.

Regarding the use of microspheres with different indices of refractionand diameters, it has been shown that there is a certain range ofmicrosphere diameters termed a “super-resolution window” wheresuper-resolution optical imaging becomes possible due to the fact thatthe geometrical optics become invalid. For microspheres with n=1.46, thesuper-resolution window is established as 2 μm<diameter<9 μm. The sizeof the super-resolution window is found to be microsphere index ofrefraction dependent. Others have argued that, when refractive indexincreases further to n=2.0, the super-resolution strength reduces andthe super-resolution window shrinks, making it undesirable to use n>1.8high-index of refraction materials for nanoimaging. Thus, the use ofhigh-index of refraction microspheres in these prior studies has beenconsidered undesirable, especially for applications in air environments.

It should be noted that imaging in the presence of a liquid has a greatpotential for developing applications in biological microscopy, as mostcell cultures and other biological samples are primarily liquid. Imagingusing semi-immersed microspheres (which has been advanced by others) hasproven to be technically complicated due to the dynamic processesassociated with a droplet's evaporation, which leads to graduallyvarying resolution and magnification. Much more stable optical imagingis obtained with the microspheres totally submerged in a liquid, asutilized in the present invention. Others have (wrongly) flatly rejectedsuch approaches.

In the present invention, the combined use of two aspects that have beenpreviously considered as negative for achieving opticalsuper-resolution, i) high index of refraction microstructures and ii)total immersion, actually results in optical super-resolution withsuperior quality as compared to other known techniques. In variousexemplary embodiments, the present invention solves the problem ofsuper-resolution optical imaging in the presence of a medium with acertain index of refraction in which the microspheres are totallyembedded. The origin of this problem is connected with the fact thatconventional low-index of refraction (n˜1.46-1.50) microspheres do notform a sufficiently high refractive index contrast with liquids,polymers, or other materials routinely used in the optical devices. Forthis reason, total immersion of these microspheres in various materialsleads to a weakening of their focusing strength and a loss of theirsuper-resolution capability.

In one exemplary embodiment, the present invention solves problems inthe art by using high-index of refraction microspheres, which aredefined as microspheres with n above 1.8. In order to realize the fullpotential of the present invention, even higher index of refractionmicrospheres are desirable. In one exemplary embodiment, barium titanateglass (BTG) microspheres with an index of refraction in the visiblerealm of ˜1.9-2.1 are used. Such microspheres form a refractive indexcontrast with ˜1.4-1.6 for water or many other liquids with indices ofrefraction similar to water. In addition, the methods of the presentinvention can be realized using microspheres with diameters varying fromseveral wavelengths (˜1-2 μm in the visible realm) up to thousands ofwavelengths. Evidence is provided that BTG microspheres with n˜2.1 anddiameters of ˜50 μm fully immersed in isopropanol (n˜1.37) allows asuperior resolution of a commercial Blu-ray® disk as compared tolow-index of refraction (n˜1.5) microspheres with similar diameters inair. The advantage of large microspheres in optical imagingapplications, for example, is associated with the very wide field ofview provided by such microspheres combined with their super-resolutioncapability. The choice of microsphere size is a tradeoff between theresolution and the field-of-view—smaller spheres (e.g. micron scale)provide better resolution at the expense of field-of-view.

The idea of using high index of refraction microspheres in combinationwith total immersion for these applications is nonobvious because themechanisms of near field optical imaging using microspheres are nottotally understood at present. The geometrical optics modeling of themagnification of these systems is mainly based on their refractive indexcontrast. This geometrical optics approach takes into account a virtualimage produced by such microspheres at a certain depth below the surfaceof the structure. However, a more complete understanding of thesuper-resolution optical imaging is based on the mechanisms of thecapturing of optical near fields by microspheres which are not wellstudied at the present time.

Referring now specifically to FIGS. 1 and 2, in two exemplaryembodiments, the optical imaging setup 10 of the present inventionincludes a sample 12 with nanoscale surface features under study and aconventional microscope objective 14. In the first exemplary embodiment(FIG. 1), the high-index of refraction microspheres 16 are deposited onthe surface of the sample 12 and immersed in a liquid droplet 18. In thesecond exemplary embodiment (FIG. 2), the high-index of refractionmicrospheres 16 are embedded in a material 20 with the ability tosolidify, such as PDMS, forming a thin film that can be transferred andattached to the surface of the sample.

Related to the first exemplary embodiment (FIG. 1), a sample with aone-dimensional surface array was obtained using a commercial Blu-ray®disk with nominal track pitch size of 300 nm, consisting of 200-nm widthstripes separated by 100-nm width grooves, as shown in FIG. 3a . The100-μm-thick transparent protection layer of the disk was peeled offbefore using the microspheres.

For super-resolution optical imaging, BTG microspheres (n˜1.9-2.1) werefully immersed in isopropanol (n˜1.37) placed on the surfaces ofsamples. The microspheres were positioned on the samples eitherindividually using an optical tapered fiber controlled by a hydraulicmicromanipulator or in groups using self-assembly in a liquid. Theisopropanol was poured on the surfaces of the samples using amicropipette to fully cover the microspheres. Both the Blu-ray® disk andthe microspheres had hydrophilic surfaces that resulted in small contactangles and good liquid infiltration.

An FS70 Mitutoyo microscope in reflection illumination mode with 100×(NA=0.9) or 20× (NA=0.4) microscope objectives was used for opticalimaging. The white light illumination was provided by a halogen lampwith 600-nm peak wavelength. The 300-nm period of Blu-ray® disk cannotbe resolved using conventional microscopy. Use of the microspheresallows a dramatic increase in the resolution. Super-resolution imagingof the Blu-ray® disk without liquid can be achieved using microsphereswith a moderate index of refraction, such as borosilicate glass(n˜1.47), soda lime glass (n˜1.51), polystyrene (n˜1.59), or sapphire(n˜1.77). However, all of these microspheres are found to lose theirimaging capability if they are completely covered with a layer ofisopropanol. These results were found to be generally consistent withprevious studies performed for silica microspheres with n˜1.46. Itshould be noted that the present invention can utilize a microscope in areflection mode, a transmission mode, a confocal configuration, afluorescence configuration, a STED configuration, a saturated patternexcitation microscopy (SPEM) configuration, a saturated structuredillumination microscopy (SSIM) configuration, etc.

High index of refraction (n˜1.9) BTG spheres showed very differentbehavior in these experiments. Without liquid infiltration, they did notproduce any images. However, they provided super-resolution opticalimaging in cases when they were totally covered with a liquid, asillustrated in FIG. 3c . The depth of focusing in FIG. 3c is below thesurface of the sample, as can be seen by comparison with the case ofnear surface focusing presented for the same liquid infiltratedstructures in FIG. 3b . It is seen that the far field virtual images ofindividual 100-nm width grooves (the dark stripes) are resolved in FIG.3c , which means resolution on the order of λ/6, well in excess of theRayleigh resolution limit for the line objects (r=0.5λ/NA) isdemonstrated.

The super-resolution capability of BTG microspheres depends on theirdiameters. A comparison of FIGS. 3b and 3c shows that all spheres withdiameter sizes˜2-20 μm and index of refraction˜1.9 immersed inisopropanol allowed the resolution of the sub-diffraction features ofthe sample. Similar optical imaging using a 50-μm BTG microsphere withindex of refraction˜2.1 immersed in isopropanol was performed, as shownin FIG. 4a . The virtual image of the Blu-ray® disk through such amicrosphere shows the sub-diffraction features of the sample withextremely high quality and contrast, as illustrated in FIG. 4b . Theseresults were compared with the optical images obtained in air using thesoda-lime microspheres with 50-μm size and an index of refraction˜1.51,as illustrated in FIGS. 4c and 4d . It should be noted that therefractive index contrasts of the BTG spheres in isopropanol (˜1.53) andsoda-lime spheres in air (˜1.51) are very close. Although in terms ofthe geometrical optics these two cases are very similar, the differencein quality of these images is obvious. The quality of optical imaging bythe totally liquid immersed high-index of refraction BTG microsphereswas found to be far superior as compared to the soda-lime microspheresin air, which can be seen by comparing the resolution, quality, andcontrast of the images in FIGS. 4b and 4d . This can be explained by theshorter wavelength of light in the liquid as compared to an air case.The image in FIG. 4b shows that by using large microspheres, thesuper-resolution can be achieved in a wide field-of-view in excess oftenths of microns. Although the resolution provided by the largemicrospheres (such as 50-μm size and larger) is somewhat reduced ascompared to the wavelength scale microspheres, it is still sufficientlyhigh for many applications. This is a very important property forpractical applications of the present invention because it reduces therequirements for the precise positioning of microspheres in thesemethods.

It should be noted that there are many contemplated technologies forobtaining the structures of the present invention. The simplest exampleis based on the deposition of high-index or refraction microspheresfollowed by liquid infiltration, as described herein above. In order tovisualize larger areas of the sample, however, a microsphere can beattached to a micromanipulator and scanned along the surface of thesample. Such microstructures can also be obtained using a semiconductortechnology. As an example, the following sequence of technological stepscan be used: i) deposition of microspheres made from a sacrificialmaterial that can be evaporated or removed via temperature treatment oretching, ii) overgrowth or layer deposition using the material with thesecond, lower index of refraction, iii) removing the sacrificialmaterial, and iv) infiltration of the spherical or cylindrical voidswith the material with the first, higher index of refraction.

The key feature of one exemplary embodiment (FIG. 2) of the presentinvention, described herein above, is that one can embed themicrospheres (or microcylinders or the like) inside a thin film that hasthe ability to solidify and that can be applied to a surface under studyas a transferable optical component. This is distinguished from otherexemplary embodiments described herein above in that instead ofpositioning microspheres (or microcylinders or the like) individually,one can apply the transferable optical component, a thin film withembedded microspheres, to the surface under study. In order to simplifyoptical observation and to enable a controllable shift of such thinfilm, its surface can be lubricated with an index matching (orotherwise) liquid or gel. The exact positioning of the microspheresrelative to the surface under study is achieved by precise lateralshifting of the thin film along the lubricated surface. Again, thematerial of the thin film containing the plurality of microstructures isone of a plastic material, a gel material with an ability to solidify, apolymer or photopolymer material with the ability to solidify, an epoxymaterial, a semisolid material, a solid material, etc. The thin filmwith embedded microstructures is applied to the surface under study andcarefully positioned using, for example, lubrication and very carefultransverse shifts to align different embedded microstructures with thesurface under study. One condition is that the thin film is located soclose to the surface under study that the embedded microstructures arelocated in a near field region of the surface under study. To this end,the thin film may be slightly pressed into the surface under study.

Although the present invention is illustrated and described herein withreference to preferred embodiments and specific examples thereof, itwill be readily apparent to those of ordinary skill in the art thatother embodiments and examples may perform similar functions and/orachieve like results. All such equivalent embodiments and examples arewithin the spirit and scope of the present invention, are contemplatedthereby, and are intended to be covered by the following claims.

What is claimed is:
 1. A super-resolution optical imaging method,comprising: providing a sample to be optically imaged; disposing aplurality of microstructures adjacent to a surface of the sample to beoptically imaged; and disposing a liquid, semi-solid, or solid materialabout the plurality of microstructures; wherein the plurality ofmicrostructures have a first index of refraction equal to or greaterthan 1.8; and wherein the material disposed about the plurality ofmicrostructures has a second index of refraction that is less than thefirst index of refraction of the plurality of microstructures.
 2. Thesuper-resolution optical imaging method of claim 1, wherein theplurality of microstructures comprise one of a plurality of microspheresand a plurality of microcylinders.
 3. The super-resolution opticalimaging method of claim 1, wherein the plurality of microstructures aredisposed adjacent to the surface of the sample to be optically imagedand subsequently the material is disposed about the plurality ofmicrostructures.
 4. The super-resolution optical imaging method of claim1, wherein the plurality of microstructures are disposed adjacent to thesurface of the sample to be optically imaged after the material isdisposed about the plurality of microstructures.
 5. The super-resolutionoptical imaging method of claim 1, wherein the second index ofrefraction is less than 1.8.
 6. The super-resolution optical imagingmethod of claim 1, further comprising optically imaging the samplethrough the plurality of microstructures and the material disposed aboutthe plurality of microstructures.
 7. The super-resolution opticalimaging method of claim 1, wherein the plurality of microstructures havediameters between a wavelength of light utilized to several thousandwavelengths of the light utilized.
 8. The super-resolution opticalimaging method of claim 1, wherein the plurality of microstructures aremade of one or more of a glass material, a crystalline material, bariumtitanate, chalcogenide, titania, zirconium oxide, zinc oxide, andsilicon.
 9. The super-resolution optical imaging method of claim 1,wherein the material disposed about the plurality of microstructurescomprises one or more of water, isopropanol, an alcohol, cyclohexane,toluene, PDMS, a gel, a polymer, and an epoxy.
 10. The super-resolutionoptical imaging method of claim 1, wherein the plurality ofmicrostructures and the material disposed about the plurality ofmicrostructures form a transferrable component that is selectivelydisposed adjacent to the surface of the sample to be optically imaged.11. A super-resolution optical imaging system, comprising: a pluralityof microstructures disposed adjacent to a surface of a sample to beoptically imaged; and a liquid, semi-solid, or solid material disposedabout the plurality of microstructures; wherein the plurality ofmicrostructures have a first index of refraction equal to or greaterthan 1.8; and wherein the material disposed about the plurality ofmicrostructures has a second index of refraction that is less than thefirst index of refraction of the plurality of microstructures.
 12. Thesuper-resolution optical imaging system of claim 11, wherein theplurality of microstructures comprise one of a plurality of microspheresand a plurality of microcylinders.
 13. The super-resolution opticalimaging system of claim 11, wherein the plurality of microstructures aredisposed adjacent to the surface of the sample to be optically imagedand subsequently the material is disposed about the plurality ofmicrostructures.
 14. The super-resolution optical imaging system ofclaim 11, wherein the plurality of microstructures are disposed adjacentto the surface of the sample to be optically imaged after the materialis disposed about the plurality of microstructures.
 15. Thesuper-resolution optical imaging system of claim 11, wherein the secondindex of refraction is less than 1.8.
 16. The super-resolution opticalimaging system of claim 11, further comprising an optical imaging devicefor optically imaging the sample through the plurality ofmicrostructures and the material disposed about the plurality ofmicrostructures.
 17. The super-resolution optical imaging system ofclaim 11, wherein the plurality of microstructures have diametersbetween a wavelength of light utilized to several thousand wavelengthsof the light utilized.
 18. The super-resolution optical imaging systemof claim 11, wherein the plurality of microstructures are made of one ormore of a glass material, a crystalline material, barium titanate,chalcogenide, titania, zirconium oxide, zinc oxide, and silicon.
 19. Thesuper-resolution optical imaging system of claim 11, wherein thematerial disposed about the plurality of microstructures comprises oneor more of water, isopropanol, an alcohol, cyclohexane, toluene, PDMS, agel, a polymer, and an epoxy.
 20. The super-resolution optical imagingsystem of claim 11, wherein the plurality of microstructures and thematerial disposed about the plurality of microstructures form atransferrable component that is selectively disposed adjacent to thesurface of the sample to be optically imaged.